Conventionally, there is known a substrate processing apparatus that performs various processes such as a cleaning or a film formation on a substrate such, e.g., a semiconductor wafer or a glass substrate.
As an example, Patent Document 1 describes a substrate processing apparatus including a multiple number of liquid processing units vertically arranged in two levels; an upper transfer arm configured to load or unload a substrate into/from upper processing units; and a lower transfer arm configured to load or unload a substrate into/from lower processing units.
Patent Document 1: Japanese Patent Laid-open Publication No. 2011-082279
The technique described in Patent document 1, however, is required to improve a throughput.
For example, in the substrate processing apparatus described in Patent Document 1, a movement range of the upper transfer arm is limited within the height range of the upper processing units, and, likewise, a movement range of the lower transfer arm is limited within the height range of the lower processing units. Thus, when a problem occurs in the upper transfer arm, for example, all of the upper processing units cannot be used, so that the throughput may be deteriorated.